a shark
this is like the little fishy and the big fishy but even worse. this is when you put your hand in the shape of a fin and ram it into someones butt crack like you are trying to kill them.
I rammed my hand into his butt crack like it was the final battle.
She put her hand in a fin shape and rammed it into my butt crack for no reason.
He rammed his hand into my butt crack like he was a shark in a butt crack war.